Falls among older adults have become a serious public health problem because they result in inevitable injuries, increase hospital admissions, threaten independence, and reduce quality of life. Falls, however, are preventable and can be reduced through exercise. There are currently a number of effective exercise-based fall interventions recommended by the Centers for Disease Control and Prevention (CDC) that can be used to address the problem of falls in older adults. However, there is little informed information on best practices in terms of comparative efficacy and cost effectiveness among the recommended intervention programs. This lack of information hinders policy makers, public health practitioners, health planners, aging service providers, and others in making decisions on how to effectively invest funds to implement the best evidence-based fall prevention programs. This project is intended to narrow this knowledge gap. Our long-term goal is to create an effective, low-cost, scalable community-based Tai Chi program to help public health practitioners and community-based organizations address the problem of falls among older adults and to help older adults maintain their health and independence in the community, thereby reducing the drain on health care spending. The overall objective of this proposal is to conduct a comparative efficacy and cost-effectiveness study of an evidence-based fall prevention program-Tai Chi: Moving for Better Balance (TCMBB). Specifically, research in this proposal will address the following two questions of parallel importance: will TCMBB be more effective compared to a CDC-recommended Strength Training program? If so, will the TCMBB be more cost effective in terms of cost per fall prevented and quality adjusted life year gained? These questions will be addressed by conducting a randomized controlled trial aimed at testing the efficacy of TCMBB and Strength Training programs relative to a Stretching control on reducing fall rate and improving balance and physical functioning. It will also evaluate whether TCMBB, compared to Strength Training, will be more cost-effective, relative to the Stretching program. The study will also address the sustainability of the effects of TCMBB intervention on the proposed outcomes. At the conclusion of the study, we will have bridged an important research-to-practice gap on the cost effectiveness of different fall prevention programs and expanded our knowledge regarding how to best invest funds for intervention programs to address the pressing problems of falls in older adults and to meet Healthy People 2020 goals for improving the health, function, and life independence of community- dwelling older adults.